Bash Script reboot in certain condition

Question

I make a bash script that calls another two bash script and reboots the system in a condition is match. The condition is: REBOOT_REQUIRED>0

#!/bin/bash

# Declare a variable used as counter in order to count the reboot requests.
declare -i REBOOT_REQUIRED=0

# Script List
RESTORE_ETHERNET_NAME='restore-eth-names.sh'
RESTORE_WIFI_DRIVER='restore-wifi-driver.sh'

#####################################
# Execute RestoreEthNames.sh script #
#####################################

echo -e "Performing Startup Checks"

chmod +x $RESTORE_ETHERNET_NAME
./$RESTORE_ETHERNET_NAME
# Store return code
RESTORE_ETHERNET_NAME_RET_CODE=$?

if [[ $RESTORE_ETHERNET_NAME_RET_CODE == 0 ]]
then
    echo -e "==> Ethernet Configuration: Ok"
else
    echo -e "==> Ethernet Configuration: Fixed"
    ((REBOOT_REQUIRED++))
fi

#######################################
# Execute RestoreWiFiDriver.sh script #
#######################################

chmod +x $RESTORE_WIFI_DRIVER
./$RESTORE_WIFI_DRIVER
# Store return code
RESTORE_WIFI_DRIVER_RET_CODE=$?

if [[ $RESTORE_WIFI_DRIVER_RET_CODE == 0 ]]
then
    echo -e "==> WiFi Driver: Ok"
else
    echo -e "==> WiFi Driver: Fixed"
    ((REBOOT_REQUIRED++))
fi

if [[ $REBOOT_REQUIRED > 0 ]]
then
    echo -e "System Reboot in 5 seconds"
    sleep 5
    reboot
fi

This script is executed at startup, adding a system service with another installation script:

################################################
# Create Service to execute scripts on startup #
################################################

if [ -e $SERVICE_FULL_PATH ]; then
   echo "File $SERVICE_FULL_PATH already exists!"
else
   echo -e "[Unit]\nDescription=Startup Script\n\n[Service]\nExecStart=$\/$SCRIPT_STARTUP_CHECKS\n\n[Install]\nWantedBy=default.target" >> $SERVICE_FULL_PATH
   chmod 664 $SERVICE_FULL_PATH
   
   # Enable the service
   systemctl enable $SERVICE_NAME
fi

The service is created correctly and the service is enabled.

The problem is that the PC enters into a reboot loop... the PC starts, at the login, after 5 seconds the system reboots again and again.

Answer 1

One issue is that you are using a string comparison operator (>). This operator will check if the left-hand-side string is lexicographically greater than the right-hand-side string.

What you instead should use is the arithmetic comparison operator -gt. The same is true for your checks of the return codes, where you should use -eq instead (although it is less of a problem there, the strings representing the two numbers will be equal if the numbers themselves are).

See e.g. here or here for more information.

That said, in the simple case of a one-digit number (REBOOT_REQUIRED should not be able to exceed 2) compared to the "one-digit string" 0 the comparison should still work as expected, so there may be something amiss in the subordinate scripts you call.

Answer 2

You're running your scripts from ./ (./$RESTORE_ETHERNET_NAME and ./$RESTORE_WIFI_DRIVER), and the working directory of services is the root path by default, which means the service actually runs the scripts from /, and I guess they are not there.

You should specify the full path for your scripts (and not the relative one), either explicitly, or - assuming that the scripts are located at the same location as the startup script - use the directory of your startup script in the full path of the scripts. You could also set the WorkingDirectory directive to the location of your scripts, but that's not the optimal solution, because that means that if your script runs any other way - and not under a service - they could still fail.

Generally speaking, during debugging, instead of actually rebooting the system, you could just run echo reboot. That way the machine wouldn't get into an infinite reboot loop, and you could have seen the output of your script using systemctl status <your service>. I assume you would have seen there something such as:

./restore-wifi-driver.sh: No such file or directory

Or any other error that would have helped you identifying the issue.

And of course - it's always possible that your restore scripts don't work as you expect, don't fix the issue and that would of course lead to an infinite loop.